A NEW GENERATION OF SOLAR DISHES

Next generation of solar dishes use less steel
Sue Major Holmes, July 18, 2009 (AP via SF Chronicle)

"Sandia National Laboratories scientist Chuck Andraka is excited about what's missing from a new generation of solar dishes…There's far less steel — about 2 tons — in the structure that supports the SunCatcher, developed for Scottsdale, Ariz.-based Stirling Energy Systems, or SES. Overall, the design is 5,000 pounds lighter than its prototype.

"Sandia morphed the SunCatcher's original rectangular design into a radial structure that looks like a 37 1/2-foot diameter satellite dish with mirrors…The lab's work on the SunCatcher was done with manufacturing in mind…[as] part of a larger effort to make solar energy more affordable…"

click to enlarge

"The newest SunCatcher version has fewer pieces, so there's less inventory to keep and fewer pieces to assemble. The design retains the functionality of the previous one but is far easier to repair…SunCatcher's developers also expect it to benefit suppliers in the hard-hit automotive industry…[because it] uses radiators [like those on automobiles] for cooling…reducing evaporation…[and providing] a huge advantage in a desert environment.

"Sandia began working with SES on the project in 2002…In 2005, Sandia installed an SES-built system…SunCatchers, each producing 25 kilowatts of electricity, will be placed in arrays covering many square miles…The modular design uses mirrors attached to a parabolic dish that focuses the sun's rays onto a receiver, which transmits heat to a Stirling engine, a sealed system filled with hydrogen."

click to enlarge

"As the gas heats and cools, its pressure rises and falls, and the change in pressure drives a piston inside the engine. That produces mechanical power, which drives a generator and makes electricity…The structure rotates to follow the sun…In a particularly bright area, a utility could remove mirrors that gather sunlight; in a cloudier coastal area, it could add some, Andraka said.

"Tessera Solar plans a 60-unit [1.5 megawatt] generation plant in Arizona or California… by January…[and] two large plants… by the end of 2012 in Southern California…Tessera also is developing a 27-megawatt West Texas project…"